Simplicity

is sine plica, without a fold; as duplicity is duplex
plica, a double fold. Conduct “without a fold” is straightforward, but thought without a fold is mere
childishness. It is “tortuity of thought” that constitutes philosophic
wisdom, and “simplicity of thought” that prepares the mind for faith.

“The flat simplicity of that reply was admirable.” —Vanbrugh and
Cibber: The Provoked Husband, i.